The USDA just released the first new hardiness zone maps since 1990. Am I still in the same zone?
High-resolution state maps are available here.
In New Hampshire, most areas are now around a quarter-zone warmer, moving a lot of the state from 5a to 5b. The eastern half of Massachusetts, and southern Mass west to Springfield, went from mostly 5b to a 6a or 6b.
For the moment, at least, you can find old maps, for comparison, here. They'll probably update them soon, though.